basic metrics of food webs

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Basic metrics of food webs S = 19 species L max = 19*18/2 = 171 possible links between two species L = 35 realized links between two species Connectance: C = 35/171 Ch = 100 total length of all food chains Li = 40 is the total number of chains ChL = 100/40 = 2.5 is the average chain length L/S = 35/19 = 1.8 is the mean number of links per species 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 S = 19 L m ax = 19x18/2=171 L = 35 C = 35 /171 = 0.2 Ch = 100 Li= 40 ChL = 100 /40 = 2.5 L /S = 35 /19 = 1.8 A pitcher plant (Nepenthes albomarginata) food web Nepenthes albomarginata

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Basic metrics of food webs. A pitcher plant ( Nepenthes albomarginata ) food web . Nepenthes albomarginata. S = 19 species L max = 19*18/2 = 171 possible links between two species L = 35 realized links between two species Connectance : C = 35/171 - PowerPoint PPT Presentation

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Page 1: Basic  metrics  of  food webs

Basic metrics of food webs

S = 19 speciesLmax = 19*18/2 = 171 possible links between two speciesL = 35 realized links between two speciesConnectance: C = 35/171Ch = 100 total length of all food chainsLi = 40 is the total number of chainsChL = 100/40 = 2.5 is the average chain lengthL/S = 35/19 = 1.8 is the mean number of links per species

1

2 3

4 5 6 7 8 9 10 11

12 13 14 15 16

17 18 19

S = 19Lmax = 19x18/2=171L = 35C = 35 / 171 = 0.2Ch = 100Li = 40ChL = 100 / 40 = 2.5L / S = 35 / 19 = 1.8

A pitcher plant (Nepenthes albomarginata) food web

Nepenthes albomarginata

Page 2: Basic  metrics  of  food webs

Food web terminology

Matrix terminology Metric

Links Number of incidences N Connectivity Matrix fill

Linkage density Mean marginal total

Web asymmetry Matrix shape

Compartments Boundary clumping Morisita, Fractal dimension

Coherence

Diversity Matrix size Nm Evenness Degree distribution d(Ni)/dI

Shared links Togetherness

Underdispersion Aggregation NODFc, NODFr

Nestedness BR, T, NODF

Overdispersion Turnover

Dependence Interaction asymmetry

Niche overlap Mean togetherness Bray-Curtis distance, coefficient of correlation

S 4 2 7 1 3 5 6 8 S

8 1 1 0 0 0 1 1 1 53 1 1 0 0 1 0 1 0 49 1 1 1 0 0 1 0 0 41 1 0 0 1 0 0 0 1 32 0 0 1 1 0 0 1 0 36 0 0 1 0 1 1 0 0 34 0 1 0 0 1 0 0 0 2

10 0 0 1 1 0 0 0 0 25 1 0 0 0 0 0 0 0 17 0 0 0 0 0 0 0 1 1

S 5 4 4 3 3 3 3 3

Food web metrics translated into matrix metrics

N = 28Fill = 28/80=0.35Dm=28/10=2.8Dn=28/8=3.5

Page 3: Basic  metrics  of  food webs

Metrics of species associations in biogeographic matrices

Species/Site a b c d e f g hA 1 1 1 1 1 1 1 1B 1 0 1 0 1 1 1 1C 1 0 1 0 1 1 1 1D 1 1 1 1 1 0 0 0E 1 1 1 1 0 0 0 0F 1 1 0 1 0 0 0 0G 1 0 0 0 1 0 0 0H 1 1 0 0 0 0 0 0I 1 1 0 0 0 0 0 0J 1 0 0 0 0 0 0 1

)1(

))((2,

SS

NNNNCS ji

ijjiji

)1()1(

))((4,

SitesSitesSpeciesSpecies

NNNNCS ji

ijjiji

)1()1(1...0.........0...1

4,

SitesSitesSpeciesSpeciesCS

ji

The C-score as a metric of negative associations

The Clumping-score as a metric of positive associations

)1()1(1...1.........1...1

4,

SitesSitesSpeciesSpeciesClumping

ji

Checkerboards

)1()1(0...1.........0...1

4,

SitesSitesSpeciesSpeciesssTogetherne

ji

The Togetherness-score as a metric of niche overlap

Page 4: Basic  metrics  of  food webs

S 1 2 3 4 5 6 7 8 Sum Score

1 1 1 1 1 0 0 0 0 4 -1.581

2 1 1 1 0 1 0 0 0 4 -0.913

3 1 1 0 1 0 1 0 0 4 -0.913

4 1 0 1 1 0 0 1 0 4 -0.913

5 1 1 0 0 1 0 0 1 4 -0.002

6 0 0 1 1 0 1 1 0 4 0.002

7 0 0 1 0 1 1 0 1 4 0.913

8 0 1 0 0 0 1 1 1 4 0.913

9 0 0 0 1 1 0 1 1 4 0.913

10 0 0 0 0 1 1 1 1 4 1.581

Sum 5 5 5 5 5 5 5 5

Score -1.414 -0.817 -0.816 -0.816 0.816 0.817 0.817 1.414

AT

AC

AC

The additive nature of the C-score

CMixed = CS – CTurn - CSegr.

Numbers of checkerboards for entries within the area AT

are a measure of spatial species turnover.

Numbers of checkerboards for entries within the area

ATC are a measure of turnover independent species segregation.

The rank correlation of matrix entries is a metric of spatial turnover.

1 11 21 32 12 2…….7 108 10

R2 = 0.347

R2 is a more liberal metric than Cturn.

The correlation of ordination scores is also a metric of turnover but even less

selective.

Page 5: Basic  metrics  of  food webs

S 1 2 3 4 5 6 7 8 Sum

1 1 1 1 1 0 0 0 0 4

2 1 1 1 0 1 0 0 0 4

3 1 1 0 1 0 1 0 0 4

4 1 0 1 1 0 0 1 0 4

5 1 1 0 0 1 0 0 1 4

6 0 0 1 1 0 1 1 0 4

7 0 0 1 0 1 1 0 1 4

8 0 1 0 0 0 1 1 1 4

9 0 0 0 1 1 0 1 1 4

10 0 0 0 0 1 1 1 1 4

Sum 5 5 5 5 5 5 5 5

Range size coherence

There are 17 embedded absences.The number of embedded absences is a measure of

species range size coherence.

Coherent range size

Scattered range size

The metric depends strongly on the ordering of rows and columns

Page 6: Basic  metrics  of  food webs

I A C M O P D F H K E B J N L G Sum1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 163 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 167 1 1 1 0 1 1 1 1 1 1 0 1 0 1 1 0 12

15 1 1 0 1 1 1 1 0 0 1 1 0 1 1 0 1 1120 1 1 1 1 1 0 1 1 1 1 1 0 0 0 0 0 104 0 0 0 1 0 1 1 1 1 1 1 0 1 1 0 0 99 1 1 1 1 0 1 0 0 1 1 0 1 0 1 0 0 9

13 1 0 1 1 0 1 1 1 1 0 1 0 1 0 0 0 92 1 0 0 1 1 0 0 1 1 0 1 0 0 0 1 0 7

11 1 0 0 1 1 0 0 0 1 0 0 0 1 0 1 0 617 1 0 1 1 1 0 0 1 0 1 0 0 0 0 0 0 618 1 1 0 0 1 1 0 1 0 0 0 0 0 0 0 1 65 0 1 1 0 0 1 1 0 0 0 0 1 0 0 0 0 58 1 0 0 0 0 0 1 0 0 0 0 1 0 0 0 0 3

16 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 26 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1

10 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 112 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 114 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 119 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1

Sum 12 11 10 10 10 10 9 9 9 8 7 6 6 6 5 4

X;Y

13;J

20;Pd

d

D

D

The measurement of nestedness

The distance concept of nestedness.

2Sp Si

ij

i 1 j 1 ij

d100 1T0.04145 SpSi D

Sort the matrix rows and olumns according to some gradient.

Define an isocline that divides the matrix into a perfectly filled and an

empty part.

The normalized squared sum of relative distances of unexpected

absences and unexpected presences is now a metric of nestednessis.

-8-6-4-202468

0 50 100

Matrix size

Z-sc

ore

Page 7: Basic  metrics  of  food webs

1 1

1 1

0 1

1 1

1 0

1 1

1 1

0 1

1 1

1 0

1 0

1 0

0 1

1 1

1 1

1 0

1 0

0 1

1 1

1 1

1 0

1 0

0 1

1 0

1 1

1 0

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0

0

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0

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0

0

0

0

1

0

0

1

0

1

0

1

1 1 1 0

1 0 1 1

0

1

1 1 1 0

1 0 1 1

0

1

0 1 1 1

1 0 1 1

0

1

0 1 1 1

1 0 1 1

0

1

1 1 0 0

1 0 1 1

0

1

1 1 0 0

1 0 1 1

0

1

1 1 0 0

1 0 1 1

0

1

1 1 0 0

1 0 1 1

0

0

0 1 1 1

1 1 1 0

0

0

0 1 1 1

1 1 1 0

0

0

1 1 0 0

1 1 1 0

0

0

1 1 0 0

1 1 1 0

0

0

1 1 0 0

1 1 1 0

0

0

1 1 0 0

1 1 1 0

0

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1 1 0 0

0 1 1 1

0

0

1 1 0 0

0 1 1 1

0

0

1 1 0 0

0 1 1 1

0

0

1 1 0 0

0 1 1 1

0

0

1 1 0 0

1 1 0 0

0

0

1 1 0 0

1 1 0 0

Nestedness among rowsN

este

dnes

s am

ong

colu

mns

c5c4c3c2c1

r5

r4

r3

r2

r1

0

0

0

0

1

1 1 0 0

1 1 0 0

0 1 1 1

1 1 1 0

1 0 1 1

c5c4c3c2c1

r5

r4

r3

r2

r1

0

0

0

0

1

1 1 0 0

1 1 0 0

0 1 1 1

1 1 1 0

1 0 1 1

c1 c2 c1 c3 c1 c4 c1 c5 c2 c3

c2 c4 c2 c5 c3 c4 c3 c5 c4 c5

Npaired=0 Npaired=67 Npaired=50 Npaired=100 Npaired=67

Npaired=50 Npaired=0 Npaired=100 Npaired=100 Npaired=100

r1

r2

r1

r3

r1

r4

r1

r5

r2

r3

r2

r4

r2

r5

r3

r4

r3

r5

r4

r5

Npaired=67

Npaired=67

Npaired=50

Npaired=50

Npaired=50

Npaired=50

Npaired=0

Npaired=0

Npaired=100

Npaired=100

Ncolumns = 63.4

Nrows = 53.4

NODF = 58.4

1 1

1 1

0 1

1 1

1 0

1 1

1 1

0 1

1 1

1 0

1 0

1 0

0 1

1 1

1 1

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1 0 1 1

0

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1 1 1 0

1 0 1 1

0

1

0 1 1 1

1 0 1 1

0

1

0 1 1 1

1 0 1 1

0

1

1 1 0 0

1 0 1 1

0

1

1 1 0 0

1 0 1 1

0

1

1 1 0 0

1 0 1 1

0

1

1 1 0 0

1 0 1 1

0

0

0 1 1 1

1 1 1 0

0

0

0 1 1 1

1 1 1 0

0

0

1 1 0 0

1 1 1 0

0

0

1 1 0 0

1 1 1 0

0

0

1 1 0 0

1 1 1 0

0

0

1 1 0 0

1 1 1 0

0

0

1 1 0 0

0 1 1 1

0

0

1 1 0 0

0 1 1 1

0

0

1 1 0 0

0 1 1 1

0

0

1 1 0 0

0 1 1 1

0

0

1 1 0 0

1 1 0 0

0

0

1 1 0 0

1 1 0 0

Nestedness among rowsN

este

dnes

s am

ong

colu

mns

c5c4c3c2c1

r5

r4

r3

r2

r1

0

0

0

0

1

1 1 0 0

1 1 0 0

0 1 1 1

1 1 1 0

1 0 1 1

c5c4c3c2c1

r5

r4

r3

r2

r1

0

0

0

0

1

1 1 0 0

1 1 0 0

0 1 1 1

1 1 1 0

1 0 1 1

c5c4c3c2c1

r5

r4

r3

r2

r1

0

0

0

0

1

1 1 0 0

1 1 0 0

0 1 1 1

1 1 1 0

1 0 1 1

c5c4c3c2c1

r5

r4

r3

r2

r1

0

0

0

0

1

1 1 0 0

1 1 0 0

0 1 1 1

1 1 1 0

1 0 1 1

c1 c2 c1 c3 c1 c4 c1 c5 c2 c3

c2 c4 c2 c5 c3 c4 c3 c5 c4 c5

Npaired=0 Npaired=67 Npaired=50 Npaired=100 Npaired=67

Npaired=50 Npaired=0 Npaired=100 Npaired=100 Npaired=100

r1

r2

r1

r3

r1

r4

r1

r5

r2

r3

r2

r4

r2

r5

r3

r4

r3

r5

r4

r5

Npaired=67

Npaired=67

Npaired=50

Npaired=50

Npaired=50

Npaired=50

Npaired=0

Npaired=0

Npaired=100

Npaired=100

Ncolumns = 63.4

Nrows = 53.4

NODF = 58.4

Nestedness based on Overlap and Decreasing Fill (NODF)

paired

( 1) ( 1)2 2

NNODF

n n m m

NODF is a gap based metric and more conservative than temperature.

Page 8: Basic  metrics  of  food webs

The disorder measure of Brualdi and Sanderson

Ho many cells must be filled or emptied to achieve a perfectly ordered matrix.The Brualdi Sanderson measure is a count of this number

Sites SitesSpecies 1 2 3 4 5 6 7 8A 1 1 1 1 1 1 1 1 8B 1 1 1 1 1 1 1 1 8C 1 1 1 1 1 1 1 1 8D 1 1 1 1 1 1 1 1 8E 1 1 1 0 1 1 1 1 7F 1 1 1 1 0 0 1 1 6G 1 1 0 1 1 0 1 0 5H 1 0 1 1 1 1 0 0 5I 1 1 1 1 0 0 0 0 4J 1 1 0 0 0 0 1 1 4K 0 1 1 0 1 1 0 0 4L 1 0 1 1 0 1 0 0 4Species 11 10 10 9 8 8 8 7

Discrepancy is a gap counting metric.

Page 9: Basic  metrics  of  food webs

How to measure species aggregation?S 50 44 46 43 47 2 7 6 3 4 1 5 15 25 24 23 29 27 26 32 33 34 30 12 28 10 9 8 31 11 13 14 19 16 20 18 35 17 22 21 45 48 49 37 40 36 41 39 42 3850 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 043 0 1 0 0 0 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 041 0 0 0 0 0 1 1 1 1 1 1 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 040 0 0 0 0 0 1 1 1 1 1 1 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 049 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 033 0 0 1 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 031 1 0 0 1 0 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 039 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 034 0 0 0 1 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 042 0 0 0 0 0 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 037 0 0 0 1 0 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 035 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 036 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 029 0 1 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 1 0 0 0 0 1 1 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 032 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 024 0 0 0 0 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 0 0 0 0 1 0 1 1 1 0 1 1 1 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 027 0 0 0 0 0 1 1 1 1 1 1 1 0 1 1 1 1 1 1 0 0 0 0 1 0 1 1 1 0 1 1 1 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 026 0 0 0 0 0 1 1 1 1 1 1 1 0 1 1 1 1 1 1 0 0 0 0 1 0 1 1 1 0 1 1 1 0 0 0 0 1 0 0 0 0 0 0 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1 0 1 1 1 0 0 0 0 0 0 0 0 0 012 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 0 0 0 0 0 0 0 0 0 010 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 0 0 0 0 0 0 0 0 0 08 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 0 0 0 0 0 0 0 0 0 09 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 0 0 0 0 0 0 0 0 0 016 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 0 0 0 0 0 0 0 0 0 06 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 0 0 0 0 0 0 0 04 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 0 0 0 0 0 0 0 01 0 0 0 1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 0 1 0 1 0 0 0 0 0 07 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 0 0 0 0 0 0 0 1 0 017 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 0 0 0 0 0 1 0 0 0 025 0 0 0 0 0 1 0 0 1 1 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 0 0 0 0 0 0 0 0 0 045 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 038 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 1 1 0 1 1 1 0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 028 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 0 0 0 0 0 0 0 0 0 046 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 044 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1 018 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 1 1 0 0 0 1 1 1 1 1 1 148 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 119 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 1 0 1 1 1 0 1 1 1 1 1 1 1 1 1 1 1 0 0 0 1 1 1 1 1 1 120 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 0 1 1 1 0 1 1 1 1 1 1 1 1 1 1 1 0 0 0 1 1 1 1 1 1 130 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 1 0 1 0 0 0 0 1 0 0 0 0 0 0 1 1 1 1 1 1 122 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 1 1 0 1 1 1 1 1 1 1 1 1 1 1 0 0 0 1 1 1 1 1 1 1

Compartmented matrix

Nearest neighbor metrics

fill

dNND

species

i

sites

jij

21 1

2

dij

species

i

sites

jij

species

i

sites

j

ii

ii

jj

jjjiij

x

xxJoinOcc

1 1

1

2

1

2

11

11

11

1111

Join count statistics

Nearest neighbour is a presence – absence metric

Join count operates on presence – absence and abundance matrices

A sum of cell entries around a focal cell multiplied by the entry of the focal cell

Other metrics proposed:MorisitaSimpson

SoerensenBlock variance

Ordination score varianceMarginal variances

NND has weak power at higher matrix fill

These metrics have very low power a moderate to small matrix size and high or

low matrix fill.

Page 10: Basic  metrics  of  food webs

Species ful guc 3pog sos 2pogdabwrosgil ter 1pogwil mil swi kor hel lip wron SumPterostichus nigrita (Paykull) 1 1 2 18 2 5 0 58 53 30 61 39 0 0 0 2 2 13Platynus assimilis (Paykull) 48 2 25 9 7 4 0 39 0 0 1 0 0 76 9 117 0 11Amara brunea (Gyllenhal) 10 4 0 40 0 5 1 0 0 0 0 0 19 0 3 1 1 9Agonum lugens (Duftshmid) 0 0 0 0 0 2 1 3 2 1 2 0 0 0 0 0 1 7Loricera pilicornis (Fabricius) 5 0 0 0 1 1 0 5 0 0 1 3 0 0 0 0 0 6Pterostichus vernalis (Panzer) 0 0 0 1 0 0 1 0 2 0 21 7 0 0 0 0 1 6Amara plebeja (Gyllenhal) 0 0 0 2 0 1 0 5 0 0 0 0 1 0 0 4 0 5Badister unipustulatus Bonelli 0 0 0 1 0 0 0 3 0 0 0 0 4 0 0 3 0 4Lasoitrechus discus (Fabricius) 0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 0 0 2Poecilus cupreus (Linnaeus) 0 0 0 2 0 0 0 0 0 0 0 0 0 1 0 0 0 2Sum 4 3 2 7 3 6 3 6 4 2 5 4 3 2 2 5 4

Abundance based metrics

The C-score extension

),,,(),,,(; cdbdcabacdbdcabadcba

ST4CACA

m(m 1)n(n 1)

The metric CA is a count of the number of abundance checkerboards in the matrix.

Other 2x2 submatrices catch matrix properties that have not well defined ecological meaning.

Page 11: Basic  metrics  of  food webs

Nestedness in abundance matricesSpecies/Sites ter wron swi dab kor wil sos 2pog 3pog gil guc mil lip hel wros ful 1pog Species WeightPterostichusstrennus(Panzer) 704 36 169 1199 13 60 17 26 187 13 0 345 4 29 394 0 428 15 3624Pterostichusmelanarius 8 141 2 9 135 1 6 188 7 180 4 8 1019 11 83 0 0 15 1802Carabusgranulatus 18 11 12 154 110 11 77 11 25 19 113 52 59 0 0 11 1 15 684Pterostichusoblongopunctatus(Fab) 7 3 22 5 13 5 28 30 5 3 4 6 0 14 24 47 0 15 216Oxypselaphusobscurus(Herbst) 13 166 7 27 48 25 0 1 278 27 85 37 0 96 96 0 80 14 986Pterostichusnigrita(Paykull) 2 5 18 1 2 0 1 39 30 2 0 53 2 61 58 0 0 13 274Pseudoophonusrufipes(DeGeer) 3 13 0 1 2 1 3 1 2 90 5 3 5 0 0 6 0 13 135Pterostichusdiligens(Sturm) 4 12 3 1 1 0 1 5 11 4 5 18 0 1 1 0 0 13 67Patrobusatrorufus(Stroem) 11 2 35 0 6 22 7 11 0 348 0 0 37 2 9 81 0 12 571Synuchusvivalis(Illiger) 51 19 14 1 12 2 4 24 1 5 10 0 0 0 0 2 0 12 145Leistusterminatus(Hellwig) 1 10 3 4 1 3 3 7 4 3 0 0 1 0 0 0 11 12 51Platynusassimilis(Paykull) 9 0 4 76 0 117 39 2 7 9 1 0 25 48 0 0 0 11 337CarabusnemoralisMuller 0 10 16 5 2 12 8 0 0 1 6 14 0 6 5 0 0 11 85Harpalus4-punctatusDejean 69 17 67 9 29 41 9 555 0 0 6 0 0 77 0 0 0 10 879Pterostichusantracinus 46 1 21 0 1 0 0 0 1 0 2 274 2 0 11 11 0 10 370Pterostichusminor(Gyllenhal) 5 1 48 1 7 2 5 2 0 0 0 0 21 0 0 28 0 10 120Amarabrunea(Gyllenhal) 4 3 1 1 0 40 10 0 19 0 1 5 0 0 0 0 0 9 84Badisterbullatus(Schrank) 5 4 1 4 2 1 0 0 7 0 0 0 0 0 0 0 2 8 26

Species 17 17 17 16 16 15 15 14 14 13 12 11 10 10 9 7 5Weight 960 454 443 1498 384 343 218 902 584 704 242 815 1175 345 681 186 522

1

1 1

100,n

i

n

ij j

ij

Nk

rWNODFc

)1()1()(2

nnmm

WNODFrWNODFcWNODF

The metric is a sum of all pairs in the matrix (first sorted accoding to species richness

then sorted according to weights), where the weight in the row/column of lower species richness is smaller than the weight in the

row/column of higher species richness

Page 12: Basic  metrics  of  food webs

  Whole matrix

  Segregated Aggregated Aggregated nested Data type PA null models A null

modelsIndependent of matrix sorting C-score Clumping score CS/Clumping PA All  

    NestPairs   A   All    Togetherness   A and PA All All  Species only

  Segregated Aggregated   Data type PA null models A null models

  Simpson dissimilarity Simpson similarity   PA No fixed - fixed    Soerensen dissimilarity Soerensen dissimilarity   PA No fixed - fixed      Morisita   A and PA No fixed - fixed All    Chao   A and PA All All

  Other joint occurrence/absence metrics

Other joint occurrence/absence metrics   PA No fixed - fixed  

Dependent of matrix sorting Whole matrix 

  Segregated Aggregated Aggregated nested Data type PA null models A null

models    NND   PA All      Block   A and PA All All    Join-coint   A and PA All All  Other distance based metrics Other distance based metrics   A and PA All All      NODF A and PA All All      BR PA All        T PA All    Species only

  Segregated Aggregated   Data type PA null models A null models

  Embedded absences     PA All  For seriation r2     PA All  

  CTurn     PA All    CSegr     PA All      Morisita   PA All  

A complete table of methods for co-occurrence analysis

Page 13: Basic  metrics  of  food webs

Pattern detection in large matrices

These programs use cluster analysis and ordination to sort the matrix according to

numbers of occurrences. Didstance metrics are then used to identify compartments.

They generate hypotheses about matrix structure.

They do not fully allow for statistical inference.

WAND: ecological network analysisPajek: software for social network analysis

KliqueFinder: software for compartment analysis

Page 14: Basic  metrics  of  food webs